The factors controlling androgen synthesis by fetal testes will be studied using different fetal ages, gonadotropic hormones and intermediate factors to determine the control mechanisms for the fetal testes. Gonadotropic stimulation of fetal testicular androgen synthesis will involve both in vitro and in vivo experiments. Fetal pituitary response to releasing hormone (GnRH), thyrotropin releasing hormone (TRH) and somatotropin releasing hormone will be quantified. The in vitro experiments will use a perfusion system that baths pituitary slices from fetal pituitaries in medium. The releasing hormones will be added to the medium and the pituitary hormone concentrations in the effluent quantified.